99d329096f
Task 176-1: Pattern2 limitation investigation - Identified 10 limitation points where only position carrier was handled - Added TODO markers for Phase 176-2/3 implementation - Created phase176-pattern2-limitations.md documentation Task 176-2: CarrierUpdateLowerer helper implementation - Implemented emit_carrier_update() helper function - Supports CounterLike and AccumulationLike UpdateExpr patterns - Added 6 unit tests (all passing) - Fail-Fast error handling for carrier/variable not found Task 176-3: Pattern2 lowerer multi-carrier extension - Extended header PHI generation for all carriers - Implemented loop update for all carriers using emit_carrier_update() - Extended ExitLine/ExitMeta construction for all carriers - Updated function call/jump args to include all carriers - 9/10 tests passing (1 pre-existing test issue) Task 176-4: E2E testing and bug fixes - Fixed Trim pattern loop_var_name overwrite bug (pattern2_with_break.rs) - Fixed InstructionRewriter latch_incoming mapping bug - All E2E tests passing (RC=0): pos + result dual-carrier loops work - test_jsonparser_parse_string_min2.hako verified Task 176-5: Documentation updates - Created phase176-completion-report.md - Updated phase175-multicarrier-design.md with completion status - Updated joinir-architecture-overview.md roadmap - Updated CURRENT_TASK.md with Phase 176 completion + Phase 177 TODO - Updated loop_pattern_space.md F-axis (multi-carrier support complete) Technical achievements: - Pattern2 now handles single/multiple carriers uniformly - CarrierInfo architecture proven to work end-to-end - Two critical bugs fixed (loop_var overwrite, latch_incoming mapping) - No regressions in existing tests Next: Phase 177 - Apply to JsonParser _parse_string full implementation
139 lines
4.4 KiB
Markdown
139 lines
4.4 KiB
Markdown
# Phase 176-1: Pattern2 Limitation Investigation - Completion Report
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**Date**: 2025-12-08
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**Status**: ✅ COMPLETE
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**Task**: Mark all single-carrier limitations in Pattern2 lowerer
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---
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## What Was Done
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Investigated `src/mir/join_ir/lowering/loop_with_break_minimal.rs` and identified **10 critical points** where the lowerer currently only handles the position carrier (`i`) and ignores `CarrierInfo.carriers`.
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### Files Modified
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1. **`src/mir/join_ir/lowering/loop_with_break_minimal.rs`**
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- Added 10 TODO comments marking limitation points
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- No code changes (read + memo level only)
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2. **`docs/development/current/main/phase176-pattern2-limitations.md`**
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- Created comprehensive limitation report
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- Detailed explanation of each limitation point
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- Impact analysis and next steps
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---
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## Limitation Points Identified
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### Easy Fixes (9 points) - Iteration-based
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1. **ValueId Allocation** (Line 172) - Only allocates for position carrier
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2. **Main Function Params** (Line 208) - Only takes `i_init`
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3. **Loop Step Call Args** (Line 214) - Only passes `i_init`
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4. **Loop Step Params** (Line 234) - Only takes `i_param`
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5. **Natural Exit Jump** (Line 257) - Only passes `i_param` to k_exit
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6. **Break Exit Jump** (Line 272) - Only passes `i_param` to k_exit
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7. **Tail Call Args** (Line 304) - Only passes `i_next`
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8. **K_Exit Params** (Line 319) - Only takes `i_exit`
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9. **ExitMeta Construction** (Line 344) - Only includes position carrier
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### Hard Fix (1 point) - Requires AST Body Analysis
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10. **Loop Body Updates** (Line 284) - Only computes `i_next = i + 1`
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- **Challenge**: Need to analyze AST body to determine carrier updates
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- **Example**: How do we know `sum = sum + x` updates the `sum` carrier?
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---
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## Key Findings
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### Architecture Issue
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The Pattern2 lowerer completely ignores `CarrierInfo.carriers`:
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```rust
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pub struct CarrierInfo {
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pub loop_var_name: String, // Used ✅
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pub loop_var_id: ValueId, // Used ✅
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pub carriers: Vec<CarrierVar>, // IGNORED ❌
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pub trim_helper: Option<TrimLoopHelper>,
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}
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```
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The function signature only takes `loop_var_name` as a separate string parameter, losing access to the full CarrierInfo structure.
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### Infrastructure Ready
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- ✅ **CarrierInfo**: Already multi-carrier ready (Phase 175)
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- ✅ **ExitMeta**: Supports `ExitMeta::multiple(vec![...])` for multi-carrier
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- ✅ **LoopHeaderPhiBuilder**: Multi-carrier ready (Phase 175)
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- ✅ **ExitPhiBuilder**: Multi-carrier ready (Phase 175)
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**Problem**: Pattern2 lowerer doesn't use these capabilities!
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---
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## Next Phase Roadmap
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### Phase 176-2: Iteration-Based Fixes
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**Difficulty**: Easy
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**Estimate**: 1-2 hours
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Fix points 1-6, 8-10 by iterating over `CarrierInfo.carriers`:
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- Allocate ValueIds for all carriers
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- Extend function params/call args/jump args
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- Build multi-carrier ExitMeta
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### Phase 176-3: Loop Body Analysis
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**Difficulty**: Hard
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**Estimate**: 3-4 hours
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Fix point 7 by analyzing AST body:
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- Track carrier assignments in loop body
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- Emit update instructions for each carrier
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- Handle complex cases (conditional updates, etc.)
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### Integration Test
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Pattern 3 (trim) with Pattern 2 shape:
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```nyash
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loop(pos < len) {
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if ch == ' ' { break }
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pos = pos + 1
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}
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```
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Verify sum/count carriers survive through break exits.
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---
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## Deliverables
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1. ✅ **TODO Comments**: 10 markers added to `loop_with_break_minimal.rs`
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2. ✅ **Limitation Report**: `phase176-pattern2-limitations.md`
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3. ✅ **Completion Report**: This document
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---
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## How to Use This Report
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For Task 176-2/3 implementers:
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1. **Read the limitation report first**: `phase176-pattern2-limitations.md`
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2. **Start with easy fixes**: Points 1-6, 8-10 (iteration-based)
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3. **Tackle hard fix last**: Point 7 (loop body analysis)
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4. **Use TODO markers as guide**: Search for `TODO(Phase 176)` in code
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5. **Test with Pattern 3**: Use trim pattern as integration test
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---
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## Related Files
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- **Main file**: `src/mir/join_ir/lowering/loop_with_break_minimal.rs`
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- **CarrierInfo**: `src/mir/join_ir/lowering/carrier_info.rs`
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- **Limitation report**: `docs/development/current/main/phase176-pattern2-limitations.md`
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- **This report**: `docs/development/current/main/phase176-1-completion-report.md`
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---
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## Conclusion
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Task 176-1 successfully identified and documented all 10 single-carrier limitations in the Pattern2 lowerer. The code is now well-marked with TODO comments, and a comprehensive analysis report is available for the next implementation phases.
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**Ready for Phase 176-2/3 implementation!** 🚀
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